Welcome to Diablo! Just kept running the areas ;)

Plague swarm was definitely most annoying for me I think I had them spawn as rares about 5 times before champs came through.. luckily I already had the haunt pack.

Not really achievement related but I'm going to start putting the staff together for Whimsyshire cause I've not done that yet and farming for a spectrum might be fun!

+1 for the rant @metta. Hellz ya!

Well, 30 more runs for the plague swarm... Nada. Here are the stats:

30 runs.
14 out of 30, Cryder's Outpost spawned.
4 out of 14, RARE plague swarm spawns, not champions.

Had a bizarre stretch where Cryder's spawned TEN times in a row, though. Not sure what the odds of that happening are, but it's probably the most useless luck I've ever had in my life.

Dude... you have bad luck.

Only advice I can give now is to keep going I guess.

I finally completed this achievement, in no small part to this thread. Had to read the part that the rare sand dweller spawns in The Forgotten Ruins about 100 times before I actually believed it. Found it around 10 runs in.

Thanks @bort and @metta.

The battlefield stores was about another 30 runs to get the Skull Sword and Skeletal Marauder, but finally knocked those down as well, posted a screenshot in the brag thread.

I have created a Guide in the appropriate section to handle these achievements.